Smokejack



pfi 6, 1948. E. 1.. WISEMAN 2,439,353

SMOKE JACK Filed Jan. 17, 1945 IN VEN TOR. EA/PL L. W/SEMAN ArroENl-"Yg;

Patented Apr. 6, 1948 UNITED STATES PATENT orrlcr.

SMOKEJACK Earl L. Wiseman, University Heights, Ohio, as-

Signor to The Swartout Company, Cleveland, Ohio, a corporation of OhioApplication January 17, 1945, Serial No. 573,237

Claims. 1

This invention relates to smoke jacks and more particulary to means ofthe fixed or stationary type for controlling the draft in fiues andperforming other desirable functions in conjunction therewith.

For the sake of illustration but without limitation the smoke jack of myinvention may be considered in the environment of a flue and thefamiliar types of stoves employed in dwellings, camp cabins, Nissen hutsand the like. Such stoves for the many years of their wide use havechronically operated too hot or too cold, requiring endless manipulationof the draft doors or openings and dampers, all subject to and at themercy of great and often continuous changes in the natural draft asinduced by outside air movement around and adjacent the top of the flue.Downdrafts forced smoke, noxious gases and ashes into the room, andchanges in the outside wind velocity alternately caused an excessiverate of combustion on the one hand or incomplete combustion on the otherhand. These things have not only caused inconveniences, burning ofgrates and injury to the stoves and flues, but have also beendetrimental to health and harzardous of the life and safety of thepersons using such stoves.

It is among the objects of my invention to provide a smoke jack toregulate the flow of products of combustion from stoves, furnaces, andthe like, in a safe and desirable manner and which on the one hand willprevent down-drafts and on the other hand will induce a substantiallyconstant aid to the natural up-draft regardless of the direction orvelocity of the outside wind. Another object is to provide a smoke jackthat is weathertight and sparkproof, i. e., prevents the ingress of rainetc. and inhibits the egress of sparks or burning parts or particles offuel. Another object is to provide a smoke jack which is lightproof orblackout proof so that no light or glow from within the end of the flueis visible through or beyond the smoke jack. Another object is toprovide a smoke jack which in its influence upon the draft through thestove or furnace and flue permits even firing, provides uniform heating,retards or eliminate the burning of grates, and preserves desirable andeconomical air-fuel ratios substantially free from disturbance due tochanges in exterior wind or atmospheric conditions. Another object is toprovide a smoke jack which will eliminate or reduce the need forcompensating check drafts and down-drafts preventers or compensators.Another object is to provide a smoke jack capable of carrying out fromall of the foregoing objects that is simple in design and construction,pleasing in appearance, and rugged, durable, and economical in itsconstruction and operation. Other objects include the provision of asmoke jack capable of carrying out the foregoing objects that is free ofmoving parts and which will perform the service desired of it underwidely varying conditions of operation.

Other objects will appear from the following description of a preferredform and embodiment of my invention reference being had to theaccompanying drawings in which Fig. 1 is avertical longitudinal sectionshowing the smoke jack of my invention mounted on and associated withthe top end of a flue, and Fig. 2 is a horizontal transverse sectiontaken along the line 2--2 of Fig. 2 being of somewhat smaller scale thanFig 1 for convenience of illustration and arranging of the figures inthe drawings. In the preferred form of my invention shown in thedrawings I have illustrated my smoke jack mounted upon and operativelyassociated with the upper and out-of-door end of a cylindrical flue Ithrough and from which emanate smoke and other products of combustion.Ordinarily the upper end of the fiue upon which the smoke jack ismounted will rise from a properly flashed roof opening, not shown,according to common practice. The smoke jack embracing my inven tioncomprises an annular storm band 2 preferably of cylindrical form and ofabout twice the diameter of the flue and disposed coaxially thereof withits upper edge 3 disposed above the upper edge 4 of the flue and withits lower edge 5 disposed lower than the upper edge 4 of the fluepreferably substantially asshown in Fig. 1. Overlying the upper edge ofthe storm band 2 in substantially fluid or weather tight relation to theupper edge 3 thereof is disposed an upper battle 6 which rises upwardlyand extendsinwardly from the upper edge 3 of the storm band preferablyin conical form. The upper bafile may conveniently have a lowercylindrical flange 1 overlying the upper-most portion of the storm bandand forming an overlapping joint therewith and centering the partscoaxially. The upper baflle 6 has a central, preferably circular,opening 8' comprising the main exhaust opening of the smoke jack definedby the upper and inner circular edge 9 of the upper baffle 6. Overlyingthe open end of the flue l is a conical cap or canopy ill, the peak ofwhich H, preferably rises a little higher than the edge 9 of the upperbaffle. The lower circular edge [2 of the cap I I! lies under and spacedbelow the upper-inner edge 9 of the upper baffle 5, preferably in underlapping relation whereby to exclude rain or weather from direct ingressinto the top of the flue.

About midway vertically between the upper edge 4 of flue and theunderside of the cap or canopy Ill is disposed an intermediate or centerbafile l5 of frusto-conical form pitched substantially at the sameinclination as are the conical surfaces of the baffle 6 and the cap H1.The

upper edge I'B of the bailie I5 defines a circular opening disposedcoaxially of the flue and in the form shown of substantially the samediameter. The center bafile I5 terminates ina lower preferably circularedge ll of substantially greater diameter than the lower edge l2 of thecap I'll, approaching the storm band more closely than the lower edge ofthe cap. The center baflle as arranged and shown in the drawings liessubstantially transversely of the path which smoke leaving the flue inits upward and outward move-- ment from the end of the flue wouldotherwise tend to take to reach the annular outlet between the cap l andthe upper baffle 6. The lineal dimension from the inner edge Hi to theouter edge ll of the center baflle l may be varied somewhat from theproportions illustrated in the drawings to modify the freedom of flow ofsmoke from the flue by making the smoke take a more tortuous pathwithout altering the net minimum cross sectional area of egress from theend of the flue to the annular outlet at 0. Thus the annular areameasured at A between the bottom edge of the cap l0 and the top of. thecenter baflie l5 and the annular area at B between the center baflle l5and the top edge 4 of the flue will remain thesame even though thecenter balfle I5 is extended inwardly to reduce the diameter of thecircular opening it. Apart from increasing the tortuousness of the path,decreasing the diameter of the opening it and/or increasing the diameterof the edge I'T will at a point also restrict the net cross-sectionalarea of the path to restrict the outflow for that reason. Where my smokejack is to be employed in climates where unusually persistent high windsare encountered, I prefer to reduce the diameter of the opening l6somewhat as a means of affording a permanent throttle of the flow ofgases from the flue through the jack.

Lying below the upper edge 4- of the flue and somewhat above the loweredge 5 of the storm band is disposed a lower annular baifle 20 offrusto-conical-form preferably pitched at sub stantially the same pitchas the cap and the center baflle. The upper inner edge 2| of the bafile2!) lies closelyadjacent and preferably substantially' tight against theouter surface of the flue l fitting there against for practical purposeswithin the range of economically manufacturing tolerances. The lowerouter edge 22 of thelbaflle 2% lies a little above, inwardly of andcoaxial with the lower circular edge. 5 of the storm band 2. Between thecircular edges 5 and 22 is an annular opening C, the area of which Iprefer to be: substantially half of the cross sectional area D of theflue As shown in the drawings the area within the circular opening Himay be substantially equal to the area of the flue, and the annular areain the horizontal plan between the edge I! and the adjacent storm bandmay also be substantially as great as the area D of the flue in the 4preferred form. In the preferred form each of the transverse annularareas A and B may substantially equal the area D of the flue. The nettransverse annular area at 0 may in the preferred form exceed the: areaD of the flue by about 30 to 40%, and the top opening 8- in the upperbattle is preferably as shown of greater area than the area of the flue,which taken with the protrusion of the cap II is no less effectivethanthe area at 0.

When: there islittle or no" air movement exteriorly or? the smokejackthe relative-heat and density of the products of combustion. willcause them to move generally as shown by the curved arrows a-a in Fig. lupwardly in somewhat tortuous paths around the inner and outer edges ofthe center bafiie and around and over the lower edge of the cap andthrough the area O and the upper outlet opening 8. Under theseconditions the smoke jack will offer little resistance to the naturaldraft since the most restricted passage in the path or paths of egressfor the smokeis greater than the area of the flue. When however, anoutside wind moves past and across the smoke jack it tends, as isunderstood in the art, to produce a low pressure area to leeward oft'liemass of the smoke jack and flue as well as a somewhat high pressurearea to windward thereof. While I am not entirely certain of all thephilosophical theories and details of the movements of air and gaseswithin and without the structure-of my invention, my tests andobservations lead me to believe that a transverse wind movement whiletending to draw gases more rapidly through the main opening 8, alsotraps outside air under the bafile 2d and forces the air through theopening C tothe interior of the storm band with the result that the netamount of smoke or products of. combustion exhausted through the opening3 remains substantially constant even though thewhole mixture of outsideair and products of combustion passing through the opening 8 increaseswith the increase of velocity of movement of outside air or wind.

If the wind passing the smoke jack has an upward inclination, as isoften incident to aslope of the roof below it, a greater rareflcationtends to be produced about the opening 8, but correspondingly a greaterpressure tends to be created belowat least part of the opening C. Thusthese efiects' tend to'balance each other and tend to keep substantiallyconstant the aid to the natural draft in the flue, respect to the smokejack and the flue as to tend more or less to enter the upper opening 8and tend to induce a down-draft in the flue, i. e., to build up apressure within the storm band tending to impair the natural draft, thenthe inclination of the cap and the center and lower baflles tend tospill any such' excess of air or air and gases downwardly and outthrough the opening C. That is to say, that wind movement which tends tobuild up pressure above the smoke jack and rareflcation'below it whilepossibly retarding the movement of smoke through the upper opening 8correspondingly tends to increase the out-flow of gases and/or air andgases through the lower opening C. In this connection I have indicatedby the broken lines L in Fig. 1 that I prefer that the edges l2, H and.22 of the cap and baifles therebelow be preferably'aligned to lierespectively in concentric circles in' the surface of a steep conewhereby tofacilitate flow to and through the lower .op-ening C and/orspilling of air and/ or gases out of the lower opening C under suchconditions as those" last above described.

With the parts proportioned substantially shown in Fig. 1 and made ofsheet metal or galvanized sheet metal as is common practice in the art,I- have found, that my smoke jack tends to increase the natural draftthrough the flue about 5 to 10% when the outside air movement issubstantially horizontal and at the rate from about 4' to 6 miles perhour. In the temperate zone this rate of air movement is generally foundeven on so called quiet days or in so called still air. My smoke jackhowever, Whether for the reason mentioned above or from reasons now Ifthe wind is so inclined with '5 unknown to me, operates in such a mannerthat as outside air movement increases up to as much as 30 or 40 milesper hour that even this greatly increased wind velocity will not tend toincrease the natural draft through the flue substantially more thanabout 20%. Similarly, if the wind velocity increases even up tohurricane speed, my

smoke jack prevents anything like proportionate increase in velocity ofmovement of gases through the flue. My observations have been that eventhese very high wind velocities will not tend to increase the velocityof flue gases more than about 20% to 25% above the unaided naturaldraft.

Thus my smoke jack tends to maintain a substantially constant anddesirable aid to the natural draft through the flue throughout a widerange of wind velocities and directions, tending always to aid thenatural draft in a desirable way and amount, never tending to obstructor impair the natural draft and always tending to hold the movement offlue gases within a desirable and substantially constant range.

To secure the several operational parts in the desired relation to eachother and to provide compact and economical means for making andassembling and/or removing and replacing some or all of the parts, Iprovide preferably three main braces or struts spaced circumferentiallyand extending longitudinally of the jack and flue. Each of the braces 30preferably lie exteriorly of the upper end of the flue and may besecured thereto by such means as metal screws 3|. Each of the braces 30passes upwardly interiorly of the inner edge 2| of the lower baffle 20which edge may be notched for that purpose if the size of the struts 30be thick enough to space the edge 2| substantially away from the outersurface of the flue. The upper ends 32 of the struts 30 are turned backat a re-entrant angle as shown in Fig. 1 and underlie the lower andouter parts of cap or canopy III which is secured thereto and supportedthereby by such means as metal screws 33. Intermediately the ends of thestruts or braces 30, gusset plates 34 are securely attached by suchmeans as metal screws 35 and each gusset 34 has supporting engagementwith the storm band and the bafiles 6, l5, and 20. The gussets arepreferably made of sheet metal, each having a main flat or body part 36extending longitudinally of the smoke jack and lying in radial planestherewithin. Each gusset has an interior turned edge or flange 31 whichlies against each of the struts 30 and receives the screw or attachingmeans 35, and each gusset has a lower turned edge 38 which liesco-extensively with the upper surface of the lower baflle 20 to which itis fixedly secured as by attaching means or screws 38'. The gussets alsohave their outer and upper most edges turned as at 39 and 40 which edgesco-extend with the storm band 2 and upper baffle 6 respectively, and arejoined in flxed relation thereto by attaching means such as the metalscrews 4I- and 42 respectively. As will appear most clearly in Fig. 1the main body parts 36 of each of the gussets is cut back to an uppernarrowness along the edge 43 and is notched at 44 to secure the outeredge I! of the middle baffle, and is cut along the line 45 to underlieand support the middle bafile in its desired angle and conicaldisposition as shown in Fig. l. The interior edge [6 of the middlebafile may be notched as may be necessary or desirable to accommodatethe struts 30, where the interior edge I6 is desired to form a circlesomewhat smaller than the circle defined by the outer faces of thestruts. Although the edge 43 is shown spaced considerably away from theedge I2 of the cap [0, there edges may lie more closely adjacent. In allevents the gussets 34 not only function structurally as above describedbut preferably contribute to the aerodynamics of the device byinhibiting circumferential currents within the storm band.

The smoke jack constructed, as above described, need contain only formsand shapes separately known in the sheet-metal working arts, and can bemade readily and economically .by means familiar to sheet-metal workers.Em-

ploying the struts and gussets above described, as I prefer, with quickattachable screws securing the bafiles, storm band and cap facilitatesassembly on the job wherever it is desirable or economical to do so.

While I have illustrated and described a preferred form of my inventionand expressed my best understanding of the manner in which theadvantages and results are obtained, various modifications, changes andimprovements will occur to those skilled in the art within theteachings, practices, and precepts of my invention, and I do not care tobe limited in the scope of my patent to the preferred form andembodiment of my invention herein illustrated and described, nor to anyparticular theory of the operation thereof or in any manner other thanby the claims appended hereto.

I claim:

1. A smoke jack adapted to be associated with and supported by the opentop end of a flue comprising a right conically formed cap with its apexdisposed substantially in the axis of the flue and with its base edge ofgreater diameter than the flue, an annular storm band having acylindrical part coaxial of the flue and extending from below the end ofthe flue to above the base edge of said conical cap and radially spacedfrom the edge of said cap and from said flue, said storm band alsocomprising an upper inturned inclined portion substantially parallelingthe conical surface of said cap and spaced therefrom and defining acentral circular opening coaxial of said flue and above the base edge ofsaid cap, the apex of said cap protruding through said opening, a middlebafile of frusto-conical form disposed substantially midway between theend of the flue and said cap and having its surface inclinedsubstantially parallel to the surface of said cap and having a circularopening coaxial of said flue and having its outer edge spaced from saidstorm band, a lower baflie of frusto-conical form pitched like said capand said middle baiiie having its inner upper edge substantiallycontacting the outer surface of said flue below the open end thereof andhaving its lower outer edge spaced from said storm band above the loweredge thereof and defining an annular opening therebetween of an areaabout one half the area of the area of said flue, vertical strutssupported by the upper end of said flue and spaced circumferentiallythereabout and having bent ends supporting said cap, and gussets havingplanar body parts lying in vertical radial planes outwardly of saidstruts and having bent edge portions secured to said struts and securedto said storm band and said lower baflle and securing same in assembledrelation, said gussets also having notched edges supporting said middlebaffle.

2. A sm'oke jack adapted to be associated with 7 and supported by theopen top end of a flue comprising a .conically formedcap with its apexdisposed substantially in the axis of the flue and with its base edge ofgreater diameter than the flue, an annular storm band having acylindrical part coaxial oi the flue and extending from below the end ofthe flue to above the base edge of said conical cap and radially spacedfrom the edge of said cap and from said flue, said storm band alsocomprising an upper inturned inclined portion substantially parallelingthe conical surface of said cap and spaced therefrom and defining acentral circular opening coaxial of said flue and above the base edge ofsaid cap, the apex of said cap protruding through said opening, a middlebaffle of frusto conical form disposed between the end of the flue andsaid cap and having its surface inclined substantially parallel to thesurface of said cap and having a circular opening coaxial of said flueand having its outer edge spaced from said storm band, and a lowerbaffle of conical form pitched similarly to said cap and said middlebailie having its inner upper edge substantiall contacting the outersurface of flue below the open end thereof and having its lower outeredge spaced from said storm band above the lower edge thereof and.defining an annular opening therebetween for the passage of air andsmoke therethrough, the outer edges of said cap and said middle andlower bafiles lying substantially in the surface of a steep cone theaxis of which substantially coincides with the axis of said flue and theapex of which liesbeyond the apex of said cap.

3. A smoke jack adapted to be associated with the open top end of a fluecomprising a conically formed cap overlying the open end of the fluewith its apex disposed substantially in the axis of the flue, annularstorm band having a cylindrical part coaxial oi the flue and extendingfrom below the open end of the flue to above the lower part of saidconical cap and radially spaced from the peripheral edge of said cap andsaid flue, said storm band also comprising an upper inturned inclinedbafile substantially paralleling the conical surface of said cap andspaced therefrom and defining a central circular opening caxial of saidflue and above the lower part of said cap, a middle bafile offrusto-conical form eh"- posed between the end of the flue and said capand having its surface inclined substantially parallel to the surface ofsaid cap and having a circular opening coaxial of said flue and havingits outer edge spaced from said storm hand, a lower baffle of'conicalform inclined substantially parallel to the surlace said cap and saidmiddle 3 and having its inner upper edge substantially tacting the outersurface of said flue below the open end thereof and having its lowerouter edge spaced from said storm band and above the lower edge of saidstorm band and defining anannular opening there-between, gussets havingplanar body, parts lying in vertical radial planes out wardly of saidflue and having bent edge portions secured to said storm band and saidand lower bafiies, said gussets also have an upwardly facing notchededge supporting said middle baiiie, and means carried by said fluesupporting said gussets and said cap.

4. A device of the class described adapted to be associated with andsupported by the open top end of a flue comprising a conically .iormedcap with its apex disposed substantially in the axis of the flue andwith its base edge of greater diameter than the flue, an annular stormband having a cylindrical part coaxial of the flue terminating in alower circular edge disposed below the end of the flue and extending toabove the base edge of said conical cap and radially spaced from theedge of said cap and from said flue, said storm band also comprising anupper inturned inclined portion substantially paralleling the conicalsurface of said cap and spaced therefrom and defining a central circularopening coaxial of said flue and above the base edge of said cap,

a middle baille of frusto-conical form disposed flue for the passage ofair and smoke therethrough, the outer edges of said cap and said middleand lower bafilles lying substantially in the surface of a steep conethe axis of which substantially coincides with the axis of said flue andthe apex of which lies beyond the apex of said cap.

' 5. A smoke jack adapted to be associated with the open end of a fluecomprising an upright conical cap overlying the end of the flue andspaced therefrom with its apex higher than its 7 base edge, spacedirusto-conical baflles disposed below the edge of said. cap and lyinggenerally parallel therewith, the base edges of said bailles along withthe base edge of said cap lying in the.

surface of a reference cone whose axis is aligned with the axis of theflue and whose apex lies above the apex of said cap, the inner edge ofthe lowermost of saidfrustoeconical bafiles engaging the upper end ofsaid flue, and a cylindrical storm band disposed coaxially of said fluehaving its lower circular edge terminating near the base edge of thelowermost of said bafiles and without said cone, and a conically formedbaiiie resting on the upper edge of said storm band and lying inwardlytherefrom substantially parallel with said cap with its inner edge alsoterminating without said cone, the space between said storm band and thebase edge of the lowermost of said bailles being less than the area ofthe flue.

EARL L. WISEMAN.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS

